With fossil fuels running out, finding alternative energy sources has become a major challenge. The British are proposing to meet this challenge by relaunching the race to produce electricity from space. A project on a comet?
In a few days’ time, the United Kingdom will be making history. The British space agency will be unveiling a program to produce solar energy from space. Now, this isn’t a totally new idea. The concept was imagined by Isaac Asimov in … 1941. The science-fiction writer paved the way. For decades, Americans, Europeans, Soviets, Chinese and Japanese alike have phosphorized on the question. With a solid motivation.
Microwave flux
In one hour, the Earth receives 300 times more energy from the daytime sun than humans consume in … a year. Exploiting this unlimited resource, as satellites do on a very small scale, offers undeniable advantages, given the excellent energy yields in space. We don’t consume any of Earth’s natural space either. And the neighbors are silent.
The many researchers who have worked on this subject have identified a number of drawbacks. Given the distances between the future electric space station and the cow floor (several thousand km), it seems appropriate to transport the electricity generated by a vast microwave beam. But that’s the theory.
An 80,000-ton plant
In reality, we only know how to convey a small flow of electrons, and only over a few hundred meters. We’re going to have to make progress. Another stumbling block is the cost of building the plant. Deploying a solar power plant beyond the Van Hallen belts only makes (economic) sense if it competes with a terrestrial power plant.
Engineers at the US Department of Energy have done the math: to power a megalopolis comparable to the Paris region, you’d need to send up a craft equipped with 3 km of solar panels and an imposing antenna. This super-satellite would weigh in at 80,000 tonnes. The equivalent of 200 International Space Stations (ISS).
According to Arianespace, it costs around one hundred million euros to place a 6-ton payload into orbit. This means just over 13,000 trips to assemble a complete power plant. That’s a hefty price to pay.
Another option is possible. Instead of assembling a meccano the size of the Enterprise, why not put a flotilla of small solar satellites into the air? Weighing around ten tonnes each, they could power the Earth with a laser beam. The advantage is that the concentrated light beam can be converted into electricity using a “target” just a few m2 in size on Earth. The conversion of microwaves, on the other hand, requires a platform of several km2.
You can also choose to save electricity. It’s cheaper, but so much less spectacular.
